The Commissary is a historic building that was constructed in 1850 as an extension of an older building at Welham Plantation, which was used as a port for shipping and receiving supplies along the Mississippi River. This building is an example of Classical Revival architecture with briquette-entre-poteaux additions. Initially, the Commissary was used as a storehouse for the plantation, but around 1900, it became a general store and post office that served not only the plantation population but also the surrounding community. In 1972, the building was moved to the Rural Life Museum, where it is now exhibited. The Commissary provides a glimpse into the past, showcasing the importance of general stores and post offices in rural communities and their role in facilitating trade and commerce.